Manufacture of coke



Patented May 26, 1953 MANUFACTURE OF COKE Samuel W. Martin, Chicago,111.,

Great Lakes Carbon Corporation,

assignor to New York,

N. Y., a corporation of Delaware No Drawing. Application August 31,1950, Serial No. 182,634

4 Claims.

This invention relates to novel compositions suitable for cokemanufacture and to processes for coking such compositions. Moreparticularly, this invention relates to compositions comprising cakingcoals and petroleum coke having properties which peculiarly render suchcoke of high utility when blended with caking coals in coke manufacture.

In accordance with well accepted and standardized practices, blastfurnace and metallurgical grade cokes are prepared by the carbonizationof various caking coals. Coking is effected by heating a caking coal ormixtures of various types of caking coal in a slot or beehive oven attemperatures up to 1204 C. during a 18 to 30 hour cycle. From an economystandpoint it is desirable to select and utilize the so-called highvolatile caking coals. However, it is known to those skilled in the artthat very few so-called high volatile caking coals are available whichcan produce satisfactory blast furnace or foundry grade coke without theblending of such coals with so-called low volatile coals of thePocohontastype. Cokes prepared from the high volatile coals do not havesu icient hardness and strength and have a tendency to degrade andproduce fines in handling. The so-called low volatile caking coals areblended with the high volatile coals to increase the surface hardness ofthe coke and thereby increase resistance of the coke to abrasion. Aspreviously mentioned, the addition of low volatile caking coals tocarbonaceous compositions intended for coke manufacture may be quitecostly, this often being due to the geographical location of such coaldeposits with respect to the coke manufacturer. In addition, the lowvolatile caking coals continue in high demand and in rather shortsupply, this being partially due to the rigid specifications which havebeen placed on such a material.

As a substitute for the low volatile caking type coals, the use of lowtemperature char has been suggested and has met with some success.However, this' type of additive varies in its properties andspecifications, nor has a constant supply of this material been assuredcoke manufacturers. The use of petroleum coke has also been suggested asa component for coke manufacture. Petroleum cokes having a volatilecontent of 8 to 13% have been admixed with high volatile caking coalsfollowed by subjecting this mixture to carbonization. These attemptshave been commercially unsuccessful, the probable reasons for which willbe subsequently pointed out herein.

,It is an object of this invention to provide a novel composition welladapted to the manufacture of hard, dense, strong metallurgical coke.

It is a further object of the invention to provide a coke suitable formetallurgical, foundry and blast furnace practice and a process for itsmanufacture.

It is a further object of this invention to provide a raw material ofuniform composition suitable for the manufacture of metallurgical andblast furnace coke.

It is still a further object of the invention to provide a process forthe manufacture of a hard, dense coke having uniform physicalproperties.

It is still a further object of the invention to provide a process forthe manufacture of blast furnace and foundry coke which obviates the useof and necessity for low volatile caking coals.

It is an additional object of the invention to provide a blast furnaceor foundry coke having a reduced. ash content.

The above objects, as well as others which will become apparent upon anunderstanding of the invention as hereinafter described, are realized bypreparing a composition comprising a mixture of caking coal andpetroleum coke. The petroleum coke component has a volatile content ofabout 14-35% by weight and is further characterized by its ability toform a hard, dense agglomerate on being heated at a temperature of about950 C. to substantially remove the volatile matter of the coke.

The petroleum coke or petroleum carbon which I employ in admixture withcaking coals is produced by the non-catalytic pyrolysis of petroleumhydrocarbons, the latter including topped crude oils, thermally crackedpetroleum residuums and/or recycle stocks from the thermal or catalyticcracking of petroleum fractions. The non-catalytic cracking of petroleumhydrocarbons involves the heating of particular petroleum fractions orcomponents to a temperature of between about 412 to 490 C. The petroleumcokes thus produced which I have found to be useful in the presentinvention have a volatile content of about 14 to about 35% by weight,this volatile content being determined in accordance with the A. S. T.M. Procedure No. D271-48 as modified for peat and lignite, and beingexclusive of water. In accordance with this procedure, a relativelysmall sample of petroleum coke is heated at 950 C. for a period of timebetween about 5 to 10 minutes. The difference in weight of the sampleprior to and after heating constitutes the vola tile content of thecoke. I have found that there are distinct and highly importantdifferences between petroleum cokes having the same volatile content,and I have further found that only those petroleum cokes having avolatile content within the aforementioned range and which, in addition,form a hard, dense coke agglomerate while being heated in accordancewith the previously mentioned ,A. 1S. T. M. procedure, or at atemperature of 950 C., are suitable for my purposes. As will besubsequently illustrated herein neither petroleum cokes having avolatile content less than about 14% nor cokes havinga volatile contentbetween 14 and 35% which Will not agglomerate or form a hard, .denseibutton" are suitable for the purposesiof this invention.

In a specific embodiment of my invention, a major portion of a highvolatile calcing coal is blended with a minor portion of petroleum coke,the latter having a volatile content of about 14 to about 35% by weightand being further characterized by its ability to form a hard, denseagslomerate on being heated at a temperature of about 950 C. tosubstantially remove the volatile matter, are intimately blended andcrushed or ground 80 that a major portion and preferably 60% of themixture, will pass through an %3" screen. This mixtur is then heated ina slot oven to a temperature of 982 1204" C. for a period of about :30to 18 hours. The resulting coke i found to b equivalent to a cokeprepared from a high volatile caking coal in admixture with a minorportion of a low volatile or Pocohontas tyne cal in coal- Slot ovens orby-product ovens are well-known in the art. These ovens are elongated,narrow, Vertical chambers which are heated from the sides. A deepvertical bed of the material to be coked is placed in the slot oven andis then coked by virtue of indirect heating through the walls.

In a further embodiment of my invention I prepare a compositioncomprising a major portion of high volatile caking coal together withminor DOltions of a low volatile caking or Pocollentas t pe eal and P rl u e h n t 9 'QUS Y described properties or characteristics. he r tiosof pe roleum coke to low volat le caking opal may be adjusted to meetthe specifications of the coke manufacturers, but in any event the totalamount of low volatile caking coal plus the petroleum coke willgenerally and prefstably e less than the unt Of hi h voiati caking coalin the mixture.

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While I may employ a petroleum coke having a volatile content of about14 to 35% by weight, which coke in addition will have the agglomeratingproperties described herein, I find it to be preferable to employ a cokehaving a volatile content of between about 16 and about 20% by weight.It will be apparent-to thoseskilled in the art that theseranges ofolatile contentimay and often do include minor amounts of petroleum cokehaving a volatile content falling outside of this range. While theimprovements described herein can be obtained by the utilization of suchmaterials, I have found it to be distinctly preferable to selectapetroleum coke wherein all of the coke has a volatile content between14 and 35% ;by Weight and preferably between 16 to 20% by weight.

In order to more fully illustrate the nature and character of myinvention, but with no intention of being limited thereby, the followingspecific examples areset .forth. .In all of these examples, the cokeswere prepared by heating a mixture of the indicated components, :ofwhich mixture would pass a screen, to :a

" temperature of 982 to 1080 c. for a period of time varying between 18to 24 hours. The 'resulting cokes are evaluated by their shatter,tumbler hardness (%+l) and tumbler stability A values. The shatter andtumbler tests were conducted in accordance with A. S. "I. M. proceduresNos. D141-48 and D249-29 respectively. The volatile matter (water free)was determined in accordance with the previously mentioned A. S. T. M.procedure.

In the examples set forth in Table I, a rather weakly caking highvolatile coal (38 to 40% V. M.) was employed as a major component. Thiswas intimately mixed with a low volatile caking coal (16 to 20% V. M.)and two petroleum cokes, one having a volatile content of 12% and whichwas of the non-agglomerating type and one having a volatile content of18% and which agglomerated when heated at 950 C. to form a hard, densebutton which would support a weight of two to three pounds or more.Acceptable values for shatter and tumbler for a coke prepared from thistype of high volatile coal are indicated in the appropriate columns inthe Control examples.

Table I l Percent Percent Percent Percent Shatter, Tumbler, Tumbler,Example If. V. V. Vol. Pet. Percent-l- Percent+ Percent-=1- Coal CoalCoke Coke 2 1 A h 71 85 7U 8U 70 30 71 .nn In a further embodiment of myinvention, a 65 It is apparent from the above results that a mixture ofto 75% by weight of high volatile caking coal and 5 to 25% by weight ofpetroleum coke is prepared and comminuted such that a major portion andpreferably at least 60% of the mixture will pass through an /8 screen.The petroleum coke should preferably have a volatile content of about 16to about 20% by weight and it is further characterized by its ability toform a hard, dense agglomerate on being heated at a temperature of about950 C. to substantially remove the volatile matter.

coke prepared from a mixture of high volatile coal and petroleum cokehaving a volatile content of 12% by weight falls considerably short ofacceptance for blast furnace coke. On the other hand, the use ofpetroleum coke having a volatile content of 18% and which willagglomerate" on heating to 950 C. equals, and in some instances,surpasses the minimum desired specifications.

In the following examples it was desired to prepare a coke suitable forblast furnace operation which would match a coke prepared from a tice,i. e. by the blending of high volatile and low high volatile caking coaland a medium volatile volatile caking coals.

Pocohontas type coal. For illustrative purposes, The above examples havebeen recited by way two petroleum cokes were selected having volatile ofillustration and not limitation. contents of 13 and 16% by weight,neither of 5 Having thus completely described the nature which wouldagglomerate when heated at 950 and character of the invention, I claim:0. in accorda ce i p ced es p e s y 1. A process for manufacturingmetallurgical scribed herein. The shatter and tumbler figures oke whichcomprises forming an intimate mixf r e n r e p s lndlcate acceptableture consisting essentially of caking coal at least l s 1 s Dartlcularlnstallce- 0 a major portion of which is of the high volatile Table IIPercent Percent Percent Percent Shatter Tumbler Tumbler gfi H. V. g xPet. Vol. Pet. Percent- 1- Percent-l Percent-I Coal hontas Coke Coke 21" 34 Control 90 39 69 7 9o 10 1a 37 27 65 so 1s 4s 39 e1 so 20 1s 40 35so The above results indicate that petroleum coke type, and five totwenty-five per cent of petrohaving a 13% volatile content is aninferior ad- 25 leum coke, the major portion of the particles of ditiveto high volatile caking coals for the manusaid mixture passing a /8 inchscreen, forming facture of blast furnace coke as is a 16% volatile adeep bed of the mixture in a narrow, vertical content petroleum cokewhich will not agglomcoking zone, coking the mixture by indirect heatcrate upon heating to 950 C. It was subseat a temperature of about 982to 1204 0., said quently indicated that the 16% V. M. coke conpetroleumcoke consisting essentially of coke havtainedasubstantial amount ofoilymaterial which ing a volatile content in the range of 14% to wasremoved during the volatile content A. S. T. about by weight asdetermined by A. S. T. M.

M. test and which could also be removed merely procedure No. D271-48 asmodified for peat and by heating the petroleum coke to a temperature oflignite, and exclusive of volatile material evolved 400 to 500 C. 35 attemperatures of 400-500 C., and further char- In the example set forthin Table III, petroacterized by forming a dense, hard, agglomerated leumcokes having several volatile contents, and coke when heated accordingto said procedure.

all of which agglomerated on heating to 950 2. The process of claim 1wherein the volatile C., were mixed with a high volatile caking coalcontent of said coke is about 16% to about 20% (38% V. M.) in theindicated amounts. The shat- 40 by weight.

ter and tumbler properties were deter- 3. The process of claim 1 furthercharacterized mined, values of +50 and +60 respectively bein that themixture contains 95% to 75% of high ing a minimum requirement for thisparticular volatile caking coal.

coke. 4. The process of claim 1 further characterized in that the coalis a mixture of a major Table III portion of high volatile caking coaland a minor portion of a low volatile caking coal, the quantity Percentshatter Tumbler, of high volatile caking coal being in excess of theExample fi t gfifii PBIZIQIHH ff total proportion of low volatile cakingcoal plus the petroleum coke. 17 1o 61 72 SAMUEL W. MAR'I'IN'. 17 20 e071 g; :3 3i 3; References Cited in the file of this patent 33 i8 Z2 Z3UNITED STATES PATENTS 32 $3 Z}, Number Name Date 1,815,918 Knowles July28, 1931 OTHER REFERENCES I have s Shown that y Selecting a D Chemistryand Industry, vol. 51, No. 22, May

leum coke having certain properties and blending 5o 27, 1932 pages 47.459, Petrolemn c k by such a coke with high volatile caking coalsand/or M u t 1,

low volatile caking coals, I have been able to pro- Industrial andEngineering Chemistry, vol. 36, duce metallurgical grade and blastfurnace coke No. 12, December 1944, pages 1140-1144, Petroof a qualitycomparable to or superior to cokes leum Coke" by Berry et a1. (Copiesavailable in prepared in accordance with conventional prac- 65Scientific Library.)

1. A PROCESS FOR MANUFACTURING METALLURGICAL COKE WHICH COMPRISESFORMING AN INTIMATE MIXTURE CONSISTING ESSENTIALLY OF CAKING COAL ATLEAST A MAJOR PORTION OF WHICH IS OF THE HIGH VOLATILE TYPE, AND FIVE TOTWENTY-FIVE PER CENT OF PETROLEUM COKE, THE MAJOR PORTION OF THEPARTICLES OF SAID MIXTURE PASSING A 1/8 INCH SCREEN, FORMING A DEEP BEDOF THE MIXTURE IN A NARROW, VERTICAL COKING ZONE, COKING THE MIXTURE BYINDIRECT HEAT AT A TEMPERATURE OF ABOUT 982* TO 1204* C., SAID PETROLEUMCOKE CONSISTING ESSENTIALLY OF COKE HAVING A VOLATILE CONTENT IN THERANGE OF 14% TO ABOUT 35% BY WEIGHT AS DETERMINED BY A.S.T.M. PROCEDURENO. D271-48 AS MODIFIED FOR PEAT AND LIGNITE, AND EXCLUSIVE OF VOLATILEMATERIAL EVOLVED AT TEMPERATURES OF 400-500* C., AND FURTHERCHARACTERIZED BY FORMING A DENSE, HARD, AGGLOMERATED COKE WHEN HEATEDACCORDING TO SAID PROCEDURE.